Searching for the missing link between depression and neurodegeneration

A study was recently done at the Washington University School of Medicine in St. Louis where researchers attempted to find markers for early detection of Alzheimer’s disease (AD). Many patients diagnosed with AD oftentimes have symptoms of depression, irritability, and apathy in addition to dementia. Dr. Catherine M. Roe decided that looking into when these symptoms begin to appear might demonstrate how AD can affect the brain and potential ways to prevent the progression of the disease. There is not much information known on whether or not depression symptoms are a direct result of the brain morphology associated with having AD or if it develops from the person realizing they are experiencing cognitive impairments. Dr. Roe did a seven-year study observing 2,416 people over the age of 50. The participants were regularly evaluated for mental function and psychological health over the study period. Each participant started the study with normal cognitive function and about half of them developed dementia further along in the research period. The people diagnosed with dementia were the first to experience mood changes such as depression. Only 15 percent of the people who did not develop dementia became depressed. The results of this study concluded that mood changes do not serve well as a marker for AD without a better understanding on how these behavioral and mood changes correlate to the disease.

            The study presented by Dr. Sara L. Weisenbach furthered this investigation with the focus on late life depression and how it is connected to AD and other neurodegenerative diseases. During her study, she found that AD is a risk factor for developing depression and the earlier the diagnosis of depression, the higher the risk was for developing AD. Weisenbach also observed that patients with late life depression and some cognitive impairment had thinner entorhinal cortices and an increased rate of atrophy. The frontal lobe was also found to be smaller in size in participants with late life depression.

            These findings help further the understanding that Roe was searching for in terms of how depression is linked to AD. The smaller size of the frontal lobe and increased atrophy due to late life depression could serve as a marker for the development of many neurodegenerative diseases. If treatment is initiated sooner to ease these symptoms of late life depression, perhaps the risk of developing AD will decrease or be prevented.

References:

Washington University in St. Louis. (2015). Depression, behavioral changes may precede memory loss in Alzheimer's. ScienceDaily. www.sciencedaily.com/releases/2015/01/150114162542.htm

Weisenbach, S. L., & Kumar, A. (2014) Current understanding of neurobiology and longitudinal course of geriatric depression. Curr Psychiatry Rep. 16(463): 1-9.